Synthesis of Functional Polypropylene Containing Hindered Phenol Stabilizers and Applications in Metallized Polymer Film Capacitors

Abstract

This paper discusses a new family of polymeric stabilizers (antioxidants) containing a polypropylene backbone and several pendant hindered phenol groups (PP-HP), with both random and tapered copolymer microstructures. They are effectively prepared by Steglich esterification of the corresponding hydroxylated polypropylene (PP-OH) copolymers with the hindered phenol molecule containing a carboxylic acid moiety. Some resulting PP-HP copolymers show significantly higher thermal-oxidative stability than the pristine PP polymer and the commercial PP products that contain a small amount of organic hindered phenol stabilizers. The better oxidative stability was also observed in PP/PP-HP blends under elevated temperatures. Overall, the PP chain degradation temperature increases with the increase of HP concentration in the matrix. The effectiveness of the PP-HP stabilizer is attributed to its comparability and cocrystallization with the PP homopolymer, which result in a uniform distribution of hindered phenol moieties. It also allows the relatively higher concentration of hindered phenol (polar) moieties in the PP (nonpolar) matrix without phase separation. In addition to the known advantages of polymer-bonded stabilizers, with low mobility and volatility to prevent loss through diffusion and/or extraction (particularly acute in films and coatings), the PP-HP thin dielectric films with uniform morphology show a higher dielectric constant and maintain low dielectric loss, particularly for the tapered PP-HP copolymers with high crystallinity.

Polyolefin elastomer grafted unsaturated hindered phenol esters: synthesis and antioxidant behavior

“…HCl and extracted with 30 ml of DCM. The organic layer was extracted by saturated naHCO 3 solution and dried over na 2 SO 4 followed by evaporation of extra solvent under reduced pressure. The chemical structures of synthesized antioxidants along with 13 C nMR spectra are shown in Figures 1 and 2 proved the potential antioxidant ability and revealed that polarity and hydrophobicity of stabilizers can be determining factors in efficiency of antioxidants.…”

“…[1][2][3] Also, radicals and active oxygens from materials which are in direct contact with foods can be responsible for severe diseases or even cancer. [4] To address the issue, it has been suggested to add sufficient amounts of stabilizers based on material type to inhibit degradation.…”

“…[6][7][8][9] This phenomenon results in reduced life time and properties of polymeric materials and possible health risks due to unwanted release of such stabilizers when polymers used for food packaging. [1,2,9] There have been research efforts to develop supramolecular stabilizers with reduced mobility and volatility to improve the long-term stability of polymeric products, especially packaging films and pipes. [10][11][12] The reports generally categorized as two approaches: stabilizer immobilization and high molecular weight, olefin-based antioxidants [13] to provide homogeneous distribution in polymer.…”

“…In order to evaluate the effect of initiator system on grafting of synthesized antioxidants, gP monomer was chosen because of the highest efficiency among synthesized stabilizers. Five initiator systems, namely MEK, DCP, DHBP, DCP/Sn(Oct) 2 , and DHBP/Sn(Oct) 2 were tested and results of FT-IR and nMR spectroscopies are shown in Figures 7 and 8, respectively. As it can be seen the intensity of peak at 1740 cm −1 , related to the ester group in gP, seems to increase in the order of DHBP/Sn(Oct) 2 > DCP/Sn(Oct) 2 > DHBP > DCP > MEK which suggests higher extents of grafting of gP onto polymer.…”

Copolymerization of 4-methyl-1-pentene with α,ω-alkenols

“…Polyethylene and polypropylene are the polyolefin resins with the largest commercial scale. It follows then that most researches on the synthesis of the functional polyolefin concern ethylene [4][5][6][7][8][9][10][11][12][13] and propylene [14][15][16][17][18] copolymerization. The investigation on the copolymerization of higher α-olefin with functional monomer was rather rare.…”